Originated from the demand for quality of service in developed countries, a contact center aims at providing customers with services such as prompt and accurate consulting information, and service handling and complaint through telephony and faxing, and improving the satisfaction level of customers as much as possible through highly efficient means such as automatic call distribution (ACD, Automatic Call Distribution), computer telephony integration (CTI, Computer Telephony Integration), and an automatic response system (IVR, Interaction Voice Response) of a stored program control switch and experienced manual agents. With the development and convergence of communications and computer technologies in recent years, the introduction of the distribution technology makes it unnecessary for manual agent representatives to work at one place. With the appearance of the automatic voice response devices, the work of the manual agent representatives is largely replaced, and in addition, a call center is capable of running uninterruptedly for 24 hours. The revolution of the Internet and the communication manners further enables the call center to process the fax, e-mail, Web access, and even teleconference and video conference based on the Internet in addition to the telephony. For different customers, hierarchical services provide different levels of services. For example, calls of VIP customers are directly forwarded to a high skill agent for services, and calls of ordinary users are first served by the automatic IVR. Quality of service (QoS, Quality of Service) refers to a capability of an IP network, namely, serving a specific service as required on an IP network across multiple underlying network technologies (MP, FR, ATM, Ethernet, SDH, MPLS, and the like). The connotation of IP QoS includes bandwidth/throughput, delay, jitter, packet loss ratio, and availability. With the development of the network technology and the change of the working manner, the agent may remotely access a CTI system through a network; for example, as a SOHO agent, the agent accesses a call center system from home. However, as video and audio are highly sensitive to the transmission delay and packet loss ratio of the network QoS, a remote agent is unlikely to access the network QoS due to the access network. If the QoS problem is not considered during call distribution, a certain customer call may be allocated to a remote agent with the unmatched QoS. For example, the customer accesses the call center by using a video telephone; however, the CTI allocates the call to an agent terminal that accesses a network through the ADSL. Owing to factors such as bandwidth and packet loss, the customer may fail to normally communicate with the agent. The satisfaction level of the customer is severely affected.